16 STOPWATCH TIMER (SWT)
16-2
EPSON
S1C17704 TECHNICAL MANUAL
16.2 BCD Counters
The stopwatch timer consists of two 4-bit BCD counters for counting 1/100 seconds and 1/10 seconds.
The count values can be read from the SWT_BCNT register.
1/100-second counter
∗
BCD100[3:0]
: 1/100 Sec. BCD Counter Value in the Stopwatch Timer BCD Counter (SWT_BCNT) Register
(D[3:0]/0x5021)
1/10-second counter
∗
BCD10[3:0]
: 1/10 Sec. BCD Counter Value in the Stopwatch Timer BCD Counter (SWT_BCNT) Register
(D[7:4]/0x5021)
Count-up pattern
To generate 100 Hz, 10 Hz, and 1 Hz signals from the 256 Hz source clock, the stopwatch timer changes the
count-up pattern for the counter as shown in Figure 16.2.1 using the feedback divider.
3
256
2
256
3
256
2
256
3
256
2
256
3
256
2
256
3
256
2
256
1/100-second counter count-up pattern 1
256 Hz
Approximate 100 Hz
(Feedback divider output)
1/100-second counter
Approximate 10 Hz
(1/100-second counter output)
Approximate 10 Hz
(1/100-second counter output)
1/10-second counter
1 Hz
(1/10-second counter output)
25
256
1/100-second counter count-up pattern 2
s
26
256
×
6 +
25
256
×
4 = 1 s
26
256
s
26
256
s
25
256
s
25
256
s
26
256
s
26
256
s
25
256
s
25
256
s
26
256
s
26
256
s
s
26
256
3
256
3
256
3
256
2
256
3
256
2
256
3
256
2
256
3
256
2
256
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
1/10-second counter count-up pattern
Figure 16.2.1 Count-up Pattern of Stopwatch Timer
The feedback divider generates an approximate 100 Hz signal with 2/256-second and 3/256-second clock
cycles from the 256 Hz signal supplied from the OSC module.
The 1/100-second counter counts the approximate 100 Hz signal output by the feedback divider and generates
an approximate 10 Hz signal with 25/256-second and 26/256-second clock cycles.
The counter counts up in 2/256-second and 3/256-second intervals, therefore the count cycle is an approximate
1/100 seconds.
The 1/10-second counter counts the approximate 10 Hz signal output by the 1/100-second counter in 4:6 ratios
to generate a 1 Hz signal.
The counter counts up in 25/256-second and 26/256-second intervals, therefore the count cycle is an
approximate 1/10 seconds.
Содержание S1C17704
Страница 1: ...TECHNICAL MANUAL S1C17704 CMOS 16 BIT SINGLE CHIP MICROCOMPUTER ...
Страница 22: ...1 OVERVIEW 1 10 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Страница 42: ...3 MEMORY MAP BUS CONTROL 3 12 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Страница 82: ...6 INTERRUPT CONTROLLER ITC 6 26 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Страница 108: ...8 CLOCK GENERATOR CLG 8 8 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
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Страница 156: ...11 16 BIT TIMERS T16 11 18 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Страница 208: ...14 8 BIT OSC1 TIMER T8OSC1 14 16 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Страница 234: ...16 STOPWATCH TIMER SWT 16 14 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
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